Phaseolus beans are cultivated in almost all continents. The common bean is produced in a wide range of cropping systems and environments, as diverse as Latin America, Africa, the Middle East, China, Europe and North America. Phaseolus beans are grown in more than 90 countries. Total production surpasses 9.6 million t, on approximately 13 million ha; the estimated value of production is more than US$4380 million. The other species of the genus have a more localized regional production. Cultivation ranges from subsistence intercropping or secondary cropping to monoculture on smallholdings in the tropics and subtropics to commercial operations.

BOTANY AND DISTRIBUTION

The genus Phaseolus includes about 55 species of annuals and semiperennials throughout the warm regions of both hemispheres. It fits botanically within the order Rosales, family Leguminosae (Fabaceae), subfamily Papilionaideae, tribe Phaseoleae, subtribe Phaseolinae. Only in the past 25 years has Phaseolinae taxonomy been agreed (Maréchal et al. 1978; Delgado Salinas 1985; Debouck 1991) and three main sections have been proposed: Phaseolus, Alepidocalyx and Minkelersia (Appendix 1). Scientific and common names for the cultivated species are given in Box 11.1.

Origin, Distribution and Diffusion

Archaeological evidence for Phaseolus origin comes from Mesoamerica and the Andes (Kaplan 1965). The oldest remains of P. vulgaris, estimated at 7000 years BP (Tehuacán, Mexico) and 8000 years BP (Ancash, Peruvian, Andes), have been revised downwards (Kaplan 1994). For P. lunatus, they are dated from 1400 years BP (Tehuacán, Mexico) and 5300 years BP (Chilca, Peruvian Andes).